It is often desirable to transport stacks of products in a continuous production environment from one processing station to the next. For example, in the production of tortillas, individual tortillas are typically formed and cooked in a continuous or semicontinuous process and are then arranged into stacks in preparation for packaging. Tortilla production is a large industry—by industry estimates, accounting for over five billion dollars in sales in 2002. The production of flat food products such as tortillas, like much of the commercial food industry, conventionally requires significant manual labor that is repetitive and boring and that may lead to injuries, such as repetitive motion injuries or injuries related to worker inattention around moving and/or hot equipment. Moreover, the use of manual labor for repetitive tasks under utilizes resources and is economically inefficient. For these reasons, the food production industry has turned increasingly to technology to eliminate or reduce tasks that are amenable to automation, freeing the workforce for more appropriately challenging tasks.
The automated transport of stacks of flat products, however, presents special challenges. For example, flour and corn tortillas are typically cooked and stacked in a continuous and flexible process resulting in multiple rows of tortillas that proceed through an oven and then a stacking process. This process results in multiple rows of stacks of tortillas, spaced at irregular intervals, on one or more relatively wide conveyors. Typically, the tortilla stacks include 10 to 20 tortillas (or more) that are then ready to be inserted into bags for retail markets. Examples of counting, inspecting, and/or stacking apparatuses are disclosed in U.S. Pat. No. 4,530,632, issued to Sela, and U.S. Pat. No. 5,720,593, issued to Pleake, both of which are hereby incorporated by reference. In the apparatus disclosed by Pleake, the tortillas are fed from a conveyor into a trajectory guide and flung through a known flight trajectory to a stacking mechanism. A shaker jostles the stack of tortillas on a movable stack plate, which is lowered to deposit the stack onto a baseplate, wherein a stack removal device moves the stack of tortillas away from the stacking assembly. The stacks of tortillas, disposed in multiple rows or lanes, are transported to a pickup area where they may be manually bagged or moved into a single row on a conveyor for delivery to packaging. Bagging systems are known that will automatically process a single row of stacks of tortillas on a conveyor, automatically inserting the stacks into bags.
The latter manual step is repetitive and inefficient. However, heretofore it has been necessary to perform this task manually for several reasons. First, the stacks of tortillas exit the stacking apparatus in multiple rows or lanes and at irregular intervals. The irregularity in the stack spacing may be attributed to placement of the tortillas prior to cooking, inspection, removal of defective products, and similar factors. Also typically, the size of the stacks, as well as the diameter of the tortillas, may vary for a given apparatus. That is, a particular cooking and stacking apparatus may be set up to produce smaller or larger tortillas, and/or to permit the number of tortillas per stack to be selected. It will be appreciated that it is intrinsically more difficult to move stacked product in an automated manner due to the tendency of the stacks to tip over (or slidably spread out) due to inertial forces and the like.
Recognizing the need for an apparatus for automatically transferring stacks of tortillas from a multi-row stacker to a single-row conveyor, U.S. Pat. No. 6,454,518, to Garcia-Balleza et al., discloses an apparatus wherein stacks of tortillas are dropped from an upper conveyor onto conveyor blocks disposed on a lower conveyor. Although the disclosed device is an improvement in the art, a disadvantage of the invention taught therein is that the stacks of tortillas may become de-stacked due to the abrupt drop onto a moving block. Another disadvantage is that the disclosed system does not appear to be amenable to use with more than one size of tortilla. Garcia-Balleza et al. shows many conventional aspects of suitable conveyor systems and is therefore also incorporated herein by reference.
A disadvantage of prior art systems for transporting stacks of product is that the stacks tend to come apart or spread out as they are transported from one conveyor to another and/or abruptly change direction or speed. De-stacked product interferes with the automation production efficiencies and generally requires manual monitoring and processing to intercept and restack or discard such product.
Therefore, there remains a need for an apparatus that automatically transports stacks of flat product and transfers stacked product arriving in multiple rows onto a conveyor in a single row, wherein the integrity of the stacked products is substantially maintained.